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Old 16th Feb 2018, 8:50 pm   #21
astral highway
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Default Re: HV PSU Question

Hello

With these sorts of tiny currents, the wire inside is unlikely to be repurposeable. It’s what is described as ‘hair wire’ in the copper recovery business, where I worked at a senior level for five years when I was younger ( a major refining group) . It breaks very easily and is literally as fragile as human hair.

As far as ‘poisonous’ oil is concerned, older EHT equipment was immersed in oil containing polychloronated biphenols / dioxin. This is toxic to aquatic life and also produced by combustion in levels where is possible for it to be transported thousands of miles, only o concentrate at a low level of the food chain and work its way up. I did a major study of a felony corporate environmental crime and prosecution in the USA as an investigative journalist and studied this inside and out.

It isn’t mortally dangerous to work around with gloves but you don’t want to be throwing it down a drain, as if present, it is hazardous waste. I say if present. It’s hard to know, so maybe assume that it is. Nor do you want to ingest it or burn it. It becomes problematic up the food chain where it kills cetaceans and is teratogenic. It was also found in the breast milk of the indigenous people of Nunavut , 5,000 KM from the point source. It had ‘grass-hoppered’ over the USA, from smokestack emissions of one secondary copper and lead refinery in particular. Finally, it had landed on lichen ingested by reindeer and then killed and eaten as a staple by the first peoples living there. The Stockholm Convention on Persistent Organic Pollutants has improved things somewhat since. I’ll stop there !
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Old 17th Feb 2018, 2:26 pm   #22
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Crikey Al, copper Baron and gumshoe! You've done more in one life than ten other men put together!
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Old 17th Feb 2018, 6:17 pm   #23
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...copper Baron and gumshoe! You've done more in one life than ten other men put together!
Ahaha, Ken! while I was in the industry, I got a sense of how destructive it was, even though it passed-off as ‘recycling’.

Years later, when I’d started working for the BBC college of journalism, I discovered that a company within the refining group that is been posted to for a project in my late 20’s had declared bankruptcy in order to avoid paying a few million dollar fine.

Only because I had been working in the industry did I have the skills and insight and technical understanding to pursue such a convoluted investigation of an investigation. I became a member of the society of environmental journalists and gained access to the prosecutors of the case as well as the Environmental Protection Agency enforcement agents. I spent two weeks in the USA doing interviews and gathering copies of thousands of pages of confiscated corporate documents, I also took a series of photos (which are on the Royal Photkhraphic Society website.). I worked round the clock in my drive to understand a hugely complex mass of data, sample results, reports and evidence.

It took me ten years, on and off , using my own time and money, and while also working on other things, to follow the story from near the beginning until the successful clean up of the contaminated site.

Biggest effort of my life in many ways. The story took me around the world conceptually and I made tens of interesting contacts. I still have follow up to do. I wrote around 35,000 words but no publisher would touch the story for fear of a lawsuit for defamation. It would break anyone, trying to defend a lawsuit by the very wealthy indeed (Lear Jet owning wealth, we’re talking !)The FT weekend invited me in and got to a whisker away from commissioning me to do a short version for their magazine, but got cold feet at the last minute. When I’m well enough, I have alternative plans that bypass this difficulty, so I’m not done yet!
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Old 18th Feb 2018, 10:25 am   #24
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Thanks for that Al, fascinating!

Back on topic, a quick search of "testing for shorted turns" brings results.

This method of testing does come with a caveat, but for the life of me l can't find out how to link to another thread! (yes,l did use the search box but I've got a hangover, sorry!)
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Old 18th Feb 2018, 11:42 am   #25
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You could have a bit of fun making a Cockroft Walton multiplier, 5 volts DC in, thousands of volts out ... watch out, they do bite

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Old 18th Feb 2018, 12:41 pm   #26
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but for the life of me l can't find out how to link to another thread!
There may be easier ways, but what I do is to open a new tab and call up the page you want to link to. Click anywhere on the URL so that it highlights in blue. Copy that (control C). Then click on your destination post, where you want the link to appear, and paste (control V).
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Old 18th Feb 2018, 4:46 pm   #27
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Johnyjf - if you are a bvws member you can see Stef Niewiadomski's circuit for a shorted turns tester in the summer 2011 edition of the Bulletin (volume.36, no32.

Bill, thanks for the tips, I'm going to start a thread on linking as I can't fathom my phone.
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Old 19th Feb 2018, 2:12 pm   #28
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Hello Again,
Thanks for the advice about the oil and the disadvantages of stripping out the old wire. I just wonder if the HV terminal are recoverable and reusable though. Also I am rather curious about the state of the laminations. I have taken some pictures as requested. Its a pity such a useful item is damaged.
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Old 19th Feb 2018, 2:18 pm   #29
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Having re-read this thread I probably leave the transformer in one piece and take it down my local recycling center where presumably they know what to do with such thinks.
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Old 19th Feb 2018, 2:54 pm   #30
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Default Re: HV PSU Question

Just a thought: the transformer looks like it was made for the Military [the number along the top of the connection diagram has a very NATO-stock-numberish feel to it].

It's not perhaps a transformer designed for 400Hz aircraft service or other non-standard higher frequency? If it is the core will be unhappy if fed 50Hz mains.
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Old 19th Feb 2018, 3:27 pm   #31
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Default Re: HV PSU Question

If you have got a signal generator and an audio amp you could sweep it over the range from 100hz to 1khz and see what frequency in sings at.
If it is good at 400hz you should be able to get several thousand volts from the secondary.
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Old 19th Feb 2018, 3:36 pm   #32
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I don't have a signal generator, but will think about what you suggest, would 100Hz from a bridge rectified input improve things? I'll have a poke about in my bits to see what I have got to play with.
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Old 19th Feb 2018, 3:44 pm   #33
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I don't think it will take DC too kindly.
It will need a sine wave to get a realistic result.
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Old 19th Feb 2018, 3:51 pm   #34
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You lot are a bad influence, I have bought a XR2206 DDS Function Signal Generator kit on eBay and am looking at a K4001 - 7W IC kit from Quasar, the relatively high impedance of the transformer primary should be OK for amp says he hopefully. Update you later.
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Old 19th Feb 2018, 3:56 pm   #35
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I should have added to the above I have a digital voltmeter with a Frequency counter function.
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Old 20th Feb 2018, 7:20 am   #36
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Default Re: HV PSU Question

Hi, these transformers are normally hermetically sealed so not easy to open. They usually contain mineral oil, not the dreaded PCB's.
Operating frequency is usually marked on the data plate, but I would suspect it would blow fuses if run at 50Hz when it should be 400Hz.

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Old 20th Feb 2018, 2:29 pm   #37
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I have just finished measuring the off-load primary current and at 246v in it was 17 m/a, not excessive in my view but what do you think? It is reinforcing my conclusion that I have a lamination problem and there isn't much I can do about. Dispose and buy another tfmr or HV source. Thanks again for the help.
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Old 20th Feb 2018, 4:33 pm   #38
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Arrow Re: HV PSU Question

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Al, apologies if you are aware, but it is oil filled!
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Ah! I see! I wasn't aware of that: perhaps I missed something. Mind you, a photograph of this xformer would have been a useful adjunct to this thread.
And since we have now seen a photograph, all of the above (and what preceded it) now makes sense: the laminations are not 'get-at-able'.

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